purchases are then verified by the prescribing pharmacy. In addition to the expenditure information, this file contains characteristics of the medication, such as the National Drug Code (NDC) identifier, the drug name, and the Multum Lexicon category. Prescribed medical events may be more difficult to analyze, since the strength of the drug and quantity purchased may vary, despite two separate prescription-events being the same chemical substance. Prescribed medical events may also be more difficult to analyze, since, unlike other recorded medical events, a pharmacy encounter does not guarantee that the medication has been administered (i.e. that the patient stuck to his or her drug regiment). This file should be thought of as containing one record per pharmacy encounter. The Dental Visits files (released annually in August) – The file contains one record for each dental visit during the calendar year. It includes dental-specific information such as the type of provider seen, if the visit was due to an accident, reason for the dental event, and any medication was prescribed. The Other Medical Expenses files (released annually in August) – This file contains one record for each medical expense that does not fit into any of the other event type categories. The events and expenditures captured in this file are overwhelmingly recorded as Glasses and Contact Lenses, with Durable Medical Equipment (such as Orthopedic items, Prostheses, Hearing Devices) also included. The Hospital Inpatient Stays files (released annually in October) – This file contains hospitalization-specific information including the date of and reason for the stay, the types of services received, and any procedure(s) undertaken during the hospital inpatient stay. The Emergency Room Visits files (released annually in September) – This file contains emergency room-specific information including the date of and reason for the visit, the types of services received, and any procedures(s) undertaken during the visit. Since many E.R. visits continue into Inpatient Hospital admissions, the spending incurred during any E.R. visit resulting in an Inpatient Hospital Admission gets transferred to the Hospital Inpatient Stays event file (identifiable using the ERHEVIDX variable) and the medical expenditure cannot be divided out between pre- and post-admission. The Outpatient Visits files (released annually in September) – This file contains information about each visit to an outpatient hospital setting, including type of test or treatment being provided, whether or not a physician was seen (and if so what specialty), and what condition or diagnosis the visit